>>reporter: we are hearing from president obama. >> will find out we will find whoever harmed our citizens and we will bring them to justice. >>reporter: as the nation waits for justice, flag fly at half staff in washington, san francisco across the country in honor of those injured and killed. good evening i'm dab ashley while we still don't know who carried out the bombing or why, there are some new clue tonight. fbi released this im among late today of shredded black backpack holding one of the becomes that exploded yesterday and this image. officials there say it may the remains of pressure cooker bomb that exploded during the marathon with devastating consequence. those injured in the bombing boy from the east bay. 11-year-old aaron hurt of mary tip east waiting at the finish line for his mom when the first bomb went off. 7 news reporter amma in boston tonight and smoke with earn's father today. >> aaron is usually an athletic energetic 11-year-old. but tonight he sedated inside children hospital boston. with his dad allen in little sister abby waiting for mom catherine to cross the m